Power-operated air blowing work apparatus

ABSTRACT

A power-operated air blowing work apparatus comprises: a volute casing including a centrifugal fan installed therein and having a front wall formed with an air intake aperture for sucking air from an atmosphere into the volute casing by the centrifugal fan; an engine mounted to the volute casing in a rear side of the volute casing and connected to the centrifugal fan for rotating the centrifugal fan; an engine casing covering the engine from behind the engine in the rear side of the volute casing, and an air suction passage communicating from inside the engine casing toward inside the front wall of the volute casing for drawing air in the engine casing toward inside the front wall of the volute casing.

TECHNICAL FIELD

The present invention relates to a power-operated air blowing workapparatus such as a blower apparatus or a dust collector apparatus, andmore particularly to an engine-driven air blowing work apparatusprovided with an air-cooling configuration to efficiently air-cool theengine which drives the air blowing fan.

BACKGROUND INFORMATION

Blower apparatuses have been conventionally known and used for blowingoff fallen leaves on the ground or the like. An example of blowerapparatuses is disclosed in JP H11-148,122 A, in which the blowerapparatus includes a centrifugal fan driven by an engine. The disclosedblower apparatus comprises a back carrier frame to be piggybacked by anoperator, a volute casing including a centrifugal fan mounted on theback carrier frame, and an air-cooled engine mounted on the back carrierframe to the rear of the volute casing for driving the fan. The volutecasing of this blower apparatus is of a two-stage structure, including afirst volute casing and a second volute casing respectively coveringfront fan blades and rear fan blades disposed on a rotating disk of acentrifugal fan, wherein the fan sucks in air through the air intakeport formed in the front wall of the first volute casing, sends the airat a given pressure and speed through a communicating air passage to anair intake port formed in the rear wall of the second volute casing, andfurther pressurizes and speeds up the air in the second volute casingbefore blowing out air from the air outlet duct of the volute casing.The air outlet duct of the volute casing is communicatingly coupled tothe blow-off tube of the blower apparatus, so that the blower apparatusfinally blows out air from the distal end of the blow-off tube.

In the disclosed blower apparatus, the communicating air passage isformed on its way with a cooling air outlet port so that a part of theair sent out from the first volute casing is blown out toward the enginefrom the cooling air outlet port to air-cool the engine.

As a part of the air sucked in the volute casing is blown out toward theengine to cool the engine in the above disclosed prior art blowerapparatus, the volute casing includes the first and the second volutecasing respectively covering the front fan blades and the rear fanblades of the centrifugal fan configured in a two stage structure andthe first volute casing and the second volute casing are connectedthrough the communicating air passage, in order to compensate thedecrease in the air sending efficiency due to the loss of air used forcooling the engine on the way from the first volute casing to the secondvolute casing. Thus, the above disclosed blower apparatus would becomplicated in structure and would be accordingly costly.

SUMMARY OF THE INVENTION

In view of the foregoing circumstances, therefore, it is a primaryobject of the present invention to provide a power-operated workapparatus such as a blower apparatus, in which an engine is efficientlycooled without complicating the structure of the volute casing tocompensate an air sending loss.

According to the present invention, the object is accomplished byproviding a power-operated air blowing work apparatus comprising: avolute casing including a centrifugal fan installed therein and having afront wall formed with an air intake aperture for sucking air into thevolute casing by the centrifugal fan; an engine mounted to the volutecasing in a rear side of the volute casing and connected to thecentrifugal fan for rotating the centrifugal fan; an engine casingcovering the engine from behind the engine in the rear side of thevolute casing, and an air suction passage communicating from inside theengine casing toward inside the front wall of the volute casing fordrawing air in the engine casing toward the front wall of the volutecasing.

With a power-operated air blowing apparatus configured as above in whichan air suction passage is provided communicating from inside the enginecasing toward inside the front wall of the volute casing for drawing airin the engine casing toward inside the front wall of the volute casing,the centrifugal fan driven by the engine sucks air from the air intakeaperture in the front wall of the volute casing and the air in theengine casing is also sucked toward inside the front wall via the airsuction passage so that the air around the engine also flows toward theair suction passage, cooling the engine.

According to the present invention, the engine casing may preferably beformed with an air intake opening for introducing air from an atmosphereinto the engine casing so that the air suction passage may draw theintroduced air toward inside the front wall of the volute casing. Withthis configuration, the air introduced from an atmosphere into theengine casing through the air intake opening flows around the enginebefore drawn to inside the front wall of the volute casing, so that theengine will be efficiently cooled by the air introduced from theatmosphere. Unlike the prior art configuration as cited above, theapparatus according to the present invention does not blow out air fromthe volute casing into the engine casing, which means there will be noloss in the fan operation, and there will be no need of forming thevolute casing of a complicated two-stage structure.

According to the present invention, the volute casing may have a rearwall formed with an air outlet aperture for directing a part of the airsucked into the volute casing through the air intake aperture to theengine casing through the air outlet aperture so that the air suctionpassage may draw the air in the engine casing toward inside the frontwall of the volute casing. With this configuration, the air directedfrom the volute casing to the engine casing flows around the enginebefore drawn to inside the front wall of the volute casing, so that theengine will be efficiently cooled by the air directed from the volutecasing. Unlike the prior art configuration as cited above, the airdirected from the volute casing to the engine is drawn back to insidethe front wall of the volute casing, which will minimize losses of thefanned air, and there will be no need of forming the volute casing of acomplicated two-stage configuration.

According to the present invention, the engine casing may preferably belined inside with a sound insulating member for preventing engine noisefrom leaking outside, and the sound insulating member may form a channelbetween the engine casing and the sound insulating material so that thechannel will serve as a part of the air suction passage. Oralternatively, the sound insulating material itself may be providedtherethrough with a penetrating hole to constitute a part of the airsuction passage. Or alternatively, the air suction passage may be formedfrom behind the volute casing, around outside the volute casing andtoward inside the front wall of the volute casing.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show how thesame may be practiced and will work, reference will now be made, by wayof example, to the accompanying drawings, in which

FIG. 1 is a right side view of a backpack blower apparatus as anembodiment of a power-operated work apparatus according to the presentinvention;

FIG. 2 is a rear view of the sound insulating member formed with airsuction passages and of the fuel tank;

FIG. 3 is a side view of the backpack blower apparatus according to thepresent invention in cross section taken along the arrowed line A-A ofFIG. 2;

FIG. 4 is a side view of the backpack blower apparatus according to thepresent invention in cross section taken along the arrowed line B-B ofFIG. 2;

FIG. 5 is a side view of the backpack blower apparatus according to thepresent invention in cross section taken along the arrowed line C-C ofFIG. 2;

FIG. 6 is a side view of the backpack blower apparatus according to thepresent invention in cross section taken along the arrowed line D-D ofFIG. 2;

FIG. 7 is a side view of another embodiment of the backpack blowerapparatus in cross section in which the sound insulating member is notformed with an air suction passage;

FIG. 8 is a side view of a further embodiment of the backpack blowerapparatus in cross section in which a bottom cover member is provided toform an air suction passage from inside the engine casing toward insidethe front wall of the volute casing; and

FIG. 9 is a side view of a backpack blower apparatus according to thepresent invention in cross section as viewed along the same line as FIG.4, but provided with an air outlet aperture in the rear wall of thevolute casing.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The invention and its embodiments can now be better understood byturning to the following detailed description of the preferredembodiments with reference to the accompanying drawings. The inventionwill hereunder be described about a backpack blower apparatus in whichthe configuration according to the present invention is employed. Itshould be understood, however, that the configuration according to thepresent invention is applicable not only to a backpack blower apparatus,but also to a hand-held blower apparatus. Further, the invention is alsoapplicable to a dust collector apparatus of a backpack type or ahand-held type.

FIG. 1 shows a right side view of a backpack blower apparatus as anembodiment of a power-operated work apparatus according to the presentinvention. The backpack blower apparatus 10 comprises a back carrierframe 11 for an operator to piggyback the apparatus, a blower unit 20mounted on the back carrier frame 11 for blowing out air, and a blow-offtube (airflow tube) 27 connected to an air outlet duct 21 b of theblower unit 20 for blowing out air from the distal end of the blow-offtube 27. In the following description, the front side means the sidewhere the operator stands to piggyback the back carrier frame 11 (i.e.the side of the back contacting member 12) with respect to the backcarrier frame 11.

The back carrier frame 11 serves for the operator to piggyback theblower unit 20, and includes a back contacting member 12 to be disposedvertically along the back of the operator and a base member 13 extendinghorizontally rearward from the lower edge of the back contacting member12, exhibiting an L-shaped side view. On the base member 13 is mountedthe blower unit 20 via vibration absorbing (or nontransmittable) memberssuch as coil springs or rubber bushings.

The blower unit 20 includes a volute casing 21, a centrifugal fan 22rotatably supported in the volute casing 21, and an internal combustionengine 23 mounted to the volute casing 21 to drive the centrifugal fan22. The volute casing 21 has a front wall formed with an air intakeaperture 21 a (shown in FIG. 4) for sucking air into the volute casingby the centrifugal fan, and has an air outlet duct 21 b on the rightside of the volute casing (shown in FIG. 1) for blowing out the airsucked in by the centrifugal fan through the air intake aperture 21 a.To the air outlet duct 21 b is communicatingly coupled a blow-off tube27 so that the air blown out from the air outlet duct 21 b will befinally blown out from the distal end of the blow-off tube 27. Thevolute casing 21 has a rear wall, but the rear wall in this embodimentis not formed with an air outlet aperture for passing air backward, i.e.toward the engine space.

Within the volute casing 21 is rotatably supported the centrifugal fan22, which includes a plurality of fan blades disposed on the frontsurface of the rotary disk. When the engine 23 drives the centrifugalfan 22, the rotating blades suck air around the front area of the rotaryblades and impel the sucked air radially outward to the innercircumferential peripheral space of the volute casing to finally blowout from the air outlet duct 21 b.

The engine 23 is mounted to the rear wall of the volute casing 21 torotate the centrifugal fan 22 with an engine casing 24 also mounted tothe volute casing 21 for covering the engine 23. The engine 23 is of anair-cooled type and is cooled by the air introduced from the atmosphereinto the engine casing 24. The engine casing 24 covers all around theengine 23 except the front side in the rear side of the volute casing21. As shown in FIGS. 3-6, the engine casing 24 is provided with an airintake opening 24 a at the upper part thereof neighboring to the upperpart of the volute casing 21 for introducing air from the atmosphere.The air intake opening 24 a is provided with a sound absorbing member 25such as a rubber sponge to suppress wind noise of the air flowingthrough the air intake opening 24 a. Also as shown in FIGS. 2-6, theengine casing 24 is lined inside with a sound insulating member 26 madeof foamed material such as polyurethane foam to inhibit the engine noisefrom leaking outside.

In the backpack blower apparatus 10 of the illustrated embodiment, theengine casing 24 is provided with an air suction passage 30 whichcommunicates toward the front wall (inside the front wall, in theillustrated embodiment) of the volute casing 21 so that the air in theengine casing 24 is drawn to the front area of the volute casing 21,being sucked by the rotating fan blades of the centrifugal fan 22. Asseen in FIGS. 2-6, the air suction passage 30 in the illustratedembodiment, is comprised of first through fourth air suction channels 31(31 a, 31 b, 31 c, 31 d) formed on the surface of the sound insulatingmember 26 confronting the engine casing 24 and extending substantiallyvertically, and of first and second air suction ducts 32 (32 a, 32 b)connecting the air suction channels 31 to the front area (inside thefront wall) of the volute casing 21.

As seen in FIGS. 2-6, the first through fourth air suction channels 31a-31 d open into the engine casing 24, with the openings 31 a 1-31 d 1located in the area containing exhaust heat from the engine 23. Theopening 31 a 1 of the first air suction channel 31 a is located at theposition confronting the intake port and the carburetor of the engine23. The opening 31 b 1 of the second air suction channel 31 b is locatedat the position confronting the ignition plugs of the engine 23. Theopening 31 c 1 of the third air suction channel 31 c is located at theposition confronting the exhaust port of the engine 23. The opening 31 d1 of the fourth air suction channel 31 d is located at the positionconfronting the muffler (silencer) of the engine 23. The openings 31 a1-31 d 1 of the respective air suction channels 31 a-31 d are formedrespectively across the areas containing exhaust heat from the engine 23as seen from the air intake opening 24 a, so that the air introducedfrom the atmosphere through the air intake opening 24 a will flowthrough the areas containing exhaust heat from the engine 23. As seen inFIG. 2, the second air suction channel 31 b joins the first air suctionchannel 31 a at the vertically middle point so that the air introducedfrom the opening 31 b 1 of the second air suction channel 31 b will flowtogether with the air introduced from the opening 31 a 1 of the firstair suction channel 31 a, while the fourth air suction channel 31 djoins the third air suction channel 31 c at the vertically middle pointso that the air introduced from the opening 31 d 1 of the fourth airsuction channel 31 d will flow together with the air introduced from theopening 31 c 1 of the third air suction channel 31 c.

The air suction ducts 32 (32 a, 32 b) are made of tubular members,respectively, and communicate air in the lower portion of the enginecasing 24 to the lower front portion of the volute casing circumventingoutside the lower part wall of the volute casing 21. The air suctionducts 32 are to draw the air in the engine casing 24 sucked through theopenings 31 a 1-31 d 1 of the air suction channels 31 a-31 d,respectively, to the front portion of the volute casing 21. The airsuction duct 32 a has an airflow inlet port which is connected to thelower end of the first air delivery channel 31 a, and has an airflowoutlet port which is connected to the lower front portion of the volutecasing 21. The air delivery duct 32 b has an airflow inlet port which isconnected to the lower end of the third air delivery channel 31 c, andhas an airflow outlet port which is connected to the lower front portionof the volute casing 21. In the Figures, is shown a fuel tank 34 also.

Hereinbelow will be described how the backpack blower apparatus 10configured as above works. As the operator starts the engine 23, thecentrifugal fan 22 rotates, and the air in the atmosphere is suckedthrough the air intake aperture 21 a in the front wall of the volutecasing 21 into the volute casing 21, and the impelled air is blown outfrom the air outlet duct 21 b, flows through the blow-off tube 27, andis finally blown out from the distal end of the blow-off tube 27. As thecentrifugal fan 22 sucks air from the atmosphere through the air intakeaperture 21 a in the front wall of the volute casing 21, the front area(including inside the front wall) of the volute casing 21 shows anegative pressure and the air in the engine casing 24 is drawn to thefront area of the volute casing 21 through the air suction passage 30constituted by the air suction channels 31 (31 a-31 d). Morespecifically, as shown by the arrows in FIGS. 3-6, the air in theatmosphere is introduced through the air intake opening 24 a formed inthe upper portion of the engine casing 24 into the engine casing 24, andthe air flows through the area containing exhaust heat of the engine 23and flows into the air suction channels 31 through the openings 31 a1-31 d 1, and is drawn to the front area of the volute casing 21 via theair suction channels 31 and the air suction ducts 32. During the aboveprocess, the air introduced into the engine casing 24 flows by theheated part of the engine 23 and carries off the heat from the engine24.

With the backpack blower apparatus 10 as configured above, the engine 23drives and rotates the centrifugal fan 22, which sucks air through theair intake aperture 21 a and blows out air from the air outlet duct 21b. As the rotating fan blades suck air, the front area in the volutecasing exhibits a negative pressure. Then, the air in the engine casing24 is sucked to the front area of the volute casing 24 via the airsuction passage 30. In this process, the air in the vicinity of theengine 23 within the engine casing 24 is sucked to the front area of thevolute casing 24 via the air suction passage 30.

According to this embodiment, in particular, the air in the atmosphereis sucked into the engine casing 24 through the air intake aperture 24a, while the air within the engine casing 24 is sucked toward the frontarea of the volute casing 21. Thus, the air from the atmosphere flowsaround the engine 23 and cools the engine 23. There is no need of theatmospheric air sucked into the volute casing 21 being partly blown outinto the engine casing 24 from the volute casing 21, and the entire airsucked in the volute casing 21 is used for the airflow into the blow-offtube 27, and the air blowing efficiency by the fan will not be decreasedand there will be no need of a complicated structure for the volutecasing such as a two-stage structure as in the aforementioned prior artapparatus to compensate a possible loss.

Among prior art blower apparatuses, there is a model that comprises avolute casing having an air intake aperture in the front wall and in therear wall of the volute casing and comprises a centrifugal fan havingfan blades on both the front surface and the rear surface of therotating disk within the volute casing so that the centrifugal fan sucksair also from the rear side of the volute casing, i.e. from inside theengine casing for cooling the engine with airflow therein, with the airin the atmosphere being introduced into the engine casing through an airintake opening of the engine casing for cooling the engine. With such aprior art model, however, the production cost of the centrifugal fanhaving fan blades on both the front surface and the rear surface of therotating disk would be accordingly high. On the contrary, with the abovedescribed embodiment, the volute casing 21 has an air intake aperture 21a only in the front wall thereof and the centrifugal fan 22 has fanblades on the front surface of the rotating disk, as the air within theengine casing 24 is sucked toward the front area of the volute casing 21via the air suction passage 30 for cooling the engine 23. This woulddecrease the production cost of the centrifugal fan 22 as compared withthe mentioned prior art model.

The inner surface of the engine casing 24 is lined with the soundinsulating member 26 in order to prevent the engine noise from leakingoutside, wherein the sound insulating member 26 is formed with the airsuction channels 31 a-31 d on the surface confronting the engine casing24, and the spaces formed by the air suction channels 31 a-31 d betweenthe sound insulating member 26 and the engine casing 24 constitute apart of the air suction passage 30. The air suction channels 31 a-31 dhave openings 31 a 1-31 d 1, respectively, which are disposed at thepositions confronting the heat exhausting portion of the engine 23.According to this structure, the air introduced into the engine casing24 through the air intake opening 24 a from the atmosphere flows nearthe heat exhausting portion of the engine 23 before entering the airsuction channels 31 a-31 d. Thus, the heat exhausting portion of theengine 23 is efficiently cooled by the air from the atmosphere. While inthe above illustrated embodiment the air suction passage 30 is formedbetween the engine casing 24 and the sound insulating member 26 by theair suction channels 31 disposed on the surface of the sound insulatingmember 26 confronting the engine casing 24, the air suction passage 30may alternatively be formed by a cylindrical bore disposed through thesound insulating member 26. In such a configuration, the opening of thecylindrical bore may preferably be arranged at positions confronting theheat exhausting portion of the engine 23 in the engine casing 24 toensure the above mentioned air-cooling function.

Further alternatively, the inlet port of the air suction duct 32 may becoupled to the space below the engine 23 as shown in FIG. 7, omittingthe air suction channels 31. In this embodiment, the air suction passage30 is constituted by the air suction duct 32 only. As the inlet port ofthe air suction duct 32 is located across the engine 23 from the airintake opening 24 a, the air introduced into the engine casing 24through the air intake opening 24 a from the atmosphere flows near theengine 23 to cool the engine 23 efficiently before entering the airsuction duct 32.

While in the above mentioned embodiment, the space within the enginecasing 23 is coupled with the space inside the front wall of the volutecasing 21 via the air suction duct 32, the configuration for the airsuction passage 30 may be different as shown in FIG. 8. In thisembodiment, an air entrance 24 b is provided below the front part of theengine within the engine casing 24 penetrating the sound insulatingmember 26, and a bottom cover member 33 is provided connecting the lowerfront part of the engine casing 24 and the lower front part of thevolute casing 21 and covering the lower wall of the volute casing 21with some space inbetween, so that the space covered by the bottom covermember 31 communicates with the space below the front part of the engine23 and with the space inside the front wall of the volute casing 21,thereby constituting the air suction passage 30.

While in the heretofore mentioned embodiments, the air intake opening 24a is provided at the upper part of the engine casing 24 for introducingair from the atmosphere, the configuration for introducing air into theengine casing 24 may be different as shown in FIG. 9. In thisembodiment, an air outlet aperture 21 c is formed in the rear wall ofthe volute casing 21 for introducing into the space within the enginecasing 24 a part of the air sucked through the air intake aperture 21 aof the volute casing 21, so that the air introduced from the outletaperture 21 c will flow around the engine 23 before flowing through theair suction passage 30 to the front area of the volute casing 21. Theengine 23 will be efficiently cooled by the air flowing around theengine 23. While, in this embodiment, a part of the air sucked from theair intake aperture 21 a of the volute casing 21 flows out into thespace within the engine casing 24, the air is drawn back to the frontarea of the volute casing 21 via the air suction passage 30, and thus adecrease in the air impelling efficiency will be minimized. So, therewill be no need of providing a complicated two-stage structure of thevolute casing unlike the prior art apparatus mentioned before. In thecase of the embodiment shown in FIG. 9, the configuration of omittingair suction channels as shown in FIG. 7 or the configuration ofproviding a bottom cover member as shown in FIG. 8 in place of the airsuction ducts may also be employed.

In the above described embodiments, a part of the air suction passage 30is constituted by the air suction ducts 32 or by the space under theengine casing 24 and the volute casing 21 covered by the bottom covermember so that the air in the lower part within the engine casing 24 isdrawn to the lower front part of the volute casing 21 passing around thelower circumferential wall of the volute casing 21. The presentinvention is not necessarily limited to such configurations. A part ofthe air suction passage 30 may be constituted by an air suction duct ora cover member provided in the upper portion of the engine casing 24 orin the side portion of the engine casing 24 so that the air in the upperportion or in the side portion within the engine casing 24 may be drawnto the front area of the volute casing 21 passing around the upperportion or the side portion of the outer wall of the volute casing 21.In such a configuration, the air intake opening 24 a of the enginecasing 24 and the entrance to the air suction passage 30 may preferablybe positioned in such a way in which the air intake opening 24 a belocated across the engine 23 or at least a part of the engine 23 fromthe entrance to the air suction passage 30 so that the air introducedfrom the air intake opening 24 a flows around the engine 23 before drawnby the air suction passage to the front area of the volute casing 21.And similar merits will be obtained.

While the invention has been described about embodiments of apower-operated backpack blower apparatus 10, the invention is applicableto a power-operated hand-held blower apparatus. The invention is alsoapplicable to a backpack dust collector or a hand-held dust collector.The same merits will be enjoyed.

What is claimed is:
 1. A power-operated air blowing work apparatuscomprising: a volute casing including a centrifugal fan installedtherein and having a front wall formed with an air intake aperture forsucking air from an atmosphere into the volute casing by the centrifugalfan; an engine mounted to the volute casing in a rear side of the volutecasing and connected to the centrifugal fan for rotating the centrifugalfan; an engine casing covering the engine from behind the engine in therear side of the volute casing, and an air suction passage communicatingfrom inside the engine casing toward inside the front wall of the volutecasing for drawing air in the engine casing toward inside the front wallof the volute casing.
 2. A power-operated air blowing work apparatus asclaimed in claim 1, wherein the engine casing is formed with an airintake opening for introducing air from an atmosphere into the enginecasing, wherein the air suction passage draws the introduced air in theengine casing toward inside the front wall of the volute casing.
 3. Apower-operated air blowing work apparatus as claimed in claim 1, whereinthe volute casing has a rear wall formed with an air outlet aperture fordirecting a part of the air sucked into the volute casing through theair intake aperture to inside the engine casing through the air outletaperture, wherein the air suction passage draws the directed air in theengine casing toward inside the front wall of the volute casing.
 4. Apower-operated air blowing work apparatus as claimed in claim 1, whereinthe engine casing is lined inside with a sound insulating member forinhibiting engine noise from leaking outside, wherein the soundinsulating member is formed with a channel on the surface thereofconfronting the engine casing, thereby constituting a part of the airsuction passage between the engine casing and the sound insulatingmember.
 5. A power-operated air blowing work apparatus as claimed inclaim 1, wherein the engine casing is lined inside with a soundinsulating member for inhibiting engine noise from leaking outside,wherein the sound insulating member itself is provided with acylindrical bore disposed therein to constitute a part of the airsuction passage through the sound insulating member.
 6. A power-operatedair blowing work apparatus as claimed in claim 1, wherein the airsuction passage is formed from behind the volute casing, around outsidethe volute casing and toward inside the front wall of the volute casing.